This section is intended to introduce various aspects of the art, which may be associated with exemplary embodiments of the present invention. This discussion is believed to assist in providing a framework to facilitate a better understanding of particular aspects of the present invention. Accordingly, it should be understood that this section should be read in this light, and not necessarily as admissions of any prior art.
A number of substances of commercial significance may be produced from natural sources, including biomass. Cellulosic biomass may be particularly suitable in this regard due to the versatility of the abundant carbohydrates found therein in various forms. As used herein, the term “cellulosic biomass” refers to a living or formerly living biological material that contains cellulose. The lignocellulosic material found in the cell walls of plants is one of the world's largest sources of carbohydrates. Materials commonly produced from cellulosic biomass may include, for example, paper and pulpwood via partial digestion, biofuels, including bioethanol by fermentation.
Development of fossil fuel alternatives derived from renewable resources have received recent attention. Cellulosic biomass has garnered particular attention in this regard due to its abundance and the versatility of the various constituents found therein, particularly cellulose and other carbohydrates. Conversion of cellulosic biomass into fuel blends and other materials typically involve extraction of cellulose and other complex carbohydrates and transformation into simpler organic molecules for further processing, including digestion processes. The processing of the cellulose biomass typically produces an intermediate liquor that contains a mixture of products, including desirable organic molecules, as well as other compounds such as lignin and/or other related products. The desirable organic molecules are typically separated for further reactions to produce fuels while other components are handled separately.
There are existing methods to process the more challenging components of the intermediate liquor, which typically include lignin and/or other related products. One typical method uses solvents or other chemicals. In such a process, complex equipment is typically required and is expensive to operate because of the solvent or chemical usage. Further, separation and filtration of these other compounds, which typically include lignin and/or other related products, following solvent removal typically create engineering issues in the transportation of these other components to where they can be disposed, which is typically a burning facility. In other existing processes, the solid conversion of lignocellulosic biomass in pre-treatment (fractionation) and cellulose hydrolysis requires high temperatures and appropriate solvation properties to fully or partially solubilize lignin and/or related products present. Upon cooling, certain lignin and/or related compounds precipitate from solution. The particle size of the recovered lignin and/or related products may be variable and too large for efficient burning, thus requiring a separate pulverizing step. Furthermore, as the mixture containing lignin and/or related compounds in solution cools, it becomes sticky (typically in the glass transition temperature range of lignin and/or related products, which is about 100° C. under ambient pressure) and tends to foul the process equipment to the point of making the process inoperable.
As evidenced by the foregoing, the efficient processing of a reaction product mixture of cellulosic biomass is a complex problem that presents immense engineering challenges. Embodiments provided by the present disclosure address these challenges and provide related advantages as well.